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/**
 * Copyright (C) 2015 Asterios Raptis
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *         http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package de.alpharogroup.model;

import java.beans.IntrospectionException;
import java.beans.PropertyDescriptor;
import java.lang.reflect.Field;
import java.lang.reflect.Method;

import org.apache.commons.lang3.StringUtils;

import de.alpharogroup.model.api.Model;
import de.alpharogroup.model.api.ObjectClassAware;
import de.alpharogroup.model.api.PropertyReflectionAwareModel;
import de.alpharogroup.model.property.PropertyResolver;

/**
 * The class {@link AbstractPropertyModel} serves as a base class for different kinds of property
 * models. By default, this class uses {@link PropertyResolver} to resolve expressions on the target
 * model object.
 *
 * @param 
 *            the generic type
 */
public abstract class AbstractPropertyModel extends ChainingModel
	implements
		ObjectClassAware,
		PropertyReflectionAwareModel
{

	/** The Constant serialVersionUID. */
	private static final long serialVersionUID = 1L;

	/**
	 * Constructor
	 *
	 * @param modelObject
	 *            The nested model object
	 */
	public AbstractPropertyModel(final Object modelObject)
	{
		super(modelObject);
	}

	/**
	 * @return The innermost model or the object if the target is not a model
	 */
	public final Object getInnermostModelOrObject()
	{
		Object object = getTarget();
		while (object instanceof Model)
		{
			final Object tmp = ((Model)object).getObject();
			if (tmp == object)
			{
				break;
			}
			object = tmp;
		}
		return object;
	}

	/**
	 * {@inheritDoc}
	 */
	@Override
	@SuppressWarnings("unchecked")
	public T getObject()
	{
		final String expression = propertyExpression();
		if (StringUtils.isEmpty(expression))
		{
			// Return a meaningful value for an empty property expression
			return (T)getInnermostModelOrObject();
		}
		else if (expression.startsWith("."))
		{
			throw new IllegalArgumentException(
				"Property expressions cannot start with a '.' character");
		}

		final Object target = getInnermostModelOrObject();
		if (target != null)
		{
			return getProperty(expression, target);
		}
		return null;
	}

	/**
	 * @return model object class
	 */
	@Override
	@SuppressWarnings("unchecked")
	public Class getObjectClass()
	{
		final String expression = propertyExpression();
		final Object target = getInnermostModelOrObject();

		if (StringUtils.isEmpty(expression))
		{
			// Return a meaningful value for an empty property expression
			return (Class)(target != null ? target.getClass() : null);
		}

		if (target != null)
		{
			try
			{
				return (Class)PropertyResolver.getPropertyClass(expression, target);
			}
			catch (final Exception e)
			{
				// ignore.
			}
		}

		else if (getTarget() instanceof ObjectClassAware)
		{
			try
			{
				final Class targetClass = ((ObjectClassAware)getTarget()).getObjectClass();
				if (targetClass != null)
				{
					final PropertyDescriptor propertyDescriptor = new PropertyDescriptor(expression,
						targetClass);
					return (Class)propertyDescriptor.getPropertyType();
				}
			}
			catch (final IntrospectionException e)
			{
				// ignore.
			}

		}
		return null;
	}

	@SuppressWarnings("unchecked")
	private T getProperty(final String expression, final Object target)
	{
		T property = null;
		property = (T)PropertyResolver.getValue(expression, target);
		return property;
	}

	/**
	 * Gets the property expression for this model
	 *
	 * @return The property expression
	 */
	public final String getPropertyExpression()
	{
		return propertyExpression();
	}

	@Override
	public Field getPropertyField()
	{
		final String expression = propertyExpression();
		if (StringUtils.isEmpty(expression) == false)
		{
			final Object target = getInnermostModelOrObject();
			if (target != null)
			{
				try
				{
					return target.getClass().getDeclaredField(expression);
				}
				catch (final Exception ignore)
				{
					// ignore.
				}
			}
		}
		return null;
	}

	/**
	 * {@inheritDoc}
	 */
	@Override
	public Method getPropertyGetter()
	{
		final String expression = propertyExpression();
		if (StringUtils.isEmpty(expression) == false)
		{
			final Object target = getInnermostModelOrObject();
			if (target != null)
			{
				try
				{
					final Class targetClass = target.getClass();
					final PropertyDescriptor propertyDescriptor = new PropertyDescriptor(expression,
						targetClass);
					return propertyDescriptor.getReadMethod();
				}
				catch (final Exception ignore)
				{
				}
			}
		}
		return null;
	}

	/**
	 * {@inheritDoc}
	 */
	@Override
	public Method getPropertySetter()
	{
		final String expression = propertyExpression();
		if (StringUtils.isEmpty(expression) == false)
		{
			final Object target = getInnermostModelOrObject();
			if (target != null)
			{
				try
				{

					final Class targetClass = target.getClass();
					final PropertyDescriptor propertyDescriptor = new PropertyDescriptor(expression,
						targetClass);
					return propertyDescriptor.getWriteMethod();
				}
				catch (final Exception ignore)
				{
				}
			}
		}
		return null;
	}

	/**
	 * @return The property expression for the component
	 */
	protected abstract String propertyExpression();

	/**
	 * Applies the property expression on the model object using the given object argument.
	 *
	 * @param object
	 *            The object that will be used when setting a value on the model object
	 */
	@Override
	@SuppressWarnings("unchecked")
	public void setObject(final T object)
	{
		final String expression = propertyExpression();
		if (StringUtils.isEmpty(expression))
		{
			final Object target = getTarget();
			if (target instanceof Model)
			{
				((Model)target).setObject(object);
			}
			else
			{
				setTarget(object);
			}
		}
		else
		{
			PropertyResolver.setValue(expression, getInnermostModelOrObject(), object);
		}
	}
}